We don't need lua

We don't run .lua scripts directly; we use imapfilter which solves its
own dependencies (uses liblua5).

packaging/debian/control

@@ -8,7 +8,7 @@ Build-Depends: debhelper (>= 9)
 
 Package: __MKIT_PROJ_PKGNAME__
 Architecture: all
-Depends: bash, imapfilter, lua, shellfu-bash, shellfu-bash-core, shellfu-bash-extras
+Depends: bash, imapfilter, shellfu-bash, shellfu-bash-core, shellfu-bash-extras
 Description: __MKIT_PROJ_TAGLINE__
  imapdomo is simple convenience wrapper around imapfilter that
  adds few more Lua functions and suggests some system to way how you can